548 GLANDS OF THE LARYNX. TRACHEA. 



upwards, sometimes extending as high as the upper border of the thy- 

 roid cartilage, and occasionally above that border. When dissected 

 from the interior of the larynx it is found covered by the aryteno-epi- 

 glottideus muscle and a fibrous membrane, which latter is attached to 

 the superior thyro-arytenoid ligament below ; to the epiglottis in front ; 

 and to the upper border of the thyroid cartilage above. If examined from 

 the exterior of the larynx, it will be seen to be covered by the thyro- 

 epiglottideus muscle. On the surface of its mucous membrane are the 

 openings of sixty or seventy small follicular glands, which are situated 

 in the sub-mucous tissue, and gives to its external surface a rough and 

 ill-dissected appearance. This mucous secretion is intended for the 

 lubrication of the chordae vocales, and is directed upon them by two 

 small valvular folds of mucous membrane, which are situated at the 

 entrance of the sacculus. 



Glands. The bodies known as the glands of the larynx, namely, the 

 epiglottic and the arytenoid are very improperly named. The former is 

 a mass of areolar and adipose tissue, situated in the triangular space 

 between the front surface of the apex of the epiglottis, the hyo-epi- 

 glottidean and the thyro-hyoidean ligament. The latter is the body 

 which forms a prominence in the aryteno-epiglottidean fold of mucous 

 membrane, and has been described among the cartilages as the aryte- 

 noid cartilage. 



Vessels and Nerves. The Arteries of the larynx are derived from 

 the superior and inferior thyroid. The nerves are the superior laryn- 

 geal and recurrent laryngeal; both branches of the pneumogastric. 

 The two nerves communicate with each other freely; but the superior 

 laryngeal is distributed principally to the mucous membrane at the en- 

 trance of the larynx ; the recurrent, to the muscles. 



THE TRACHEA. 



The TRACHEA extends from opposite the fifth cervical vertebra to 

 opposite the third dorsal, where it divides into the two bronchi. The 

 right bronchus, larger than the left, passes off nearly at right angles 

 to the upper part of the corresponding lung. The left descends 

 obliquely, and passes beneath the arch of the aorta, to reach the left 

 lung. 



The Trachea is composed of 



Fibro-cartilaginous rings, 

 Fibrous membrane, 

 Mucous membrane, 

 Longitudinal elastic fibres, 

 Muscular fibres, 

 Glands. 



" Phrygian casque," and Morgagni's figure, Advers. 1. Epist. Anat. 3. plate 2. 

 fig. 4. has the same appearance. But neither of these anatomists notice the fol- 

 licular glands described by Mr. Hilton. 



